What I would like to do is to take some unsweetened chocolate, melt it down
and add an artificial sweetener (AS) so that I end up with sweetened
chocolate.

My question is, at what point in the tempering process is it best to add the
AS?

And, does it make a difference if the AS is liquid or granular?

And, if I want to add some nuts, when during the tempering process would be
the best time to add those?

Thanks for you help,
Randy